Development of a Measurement System to Determine the Circumferential Force on a Feather Key

Shaft-hub-connections are essential for the transmission of torques in drivetrains. In particular, feather key connections are frequently used due to their ease of assembly and disassembly and the resulting interchangeability. The purpose of the study is to develop a measuring system for recording the strains occurring on the feather key end face, whereby the feather key is designed as a sensor-integrated machine element. The subject of this article is the integration of a sensor into the feather key in order to record the torques transmitting across the connection. Feather keys are subjected to uneven surface pressures, which leads to complex deformation. In order to record this deformation, measurements with many strain gauges would normally be necessary. In preliminary work, the geometry of the feather key was adapted based on topology optimisation methods such that it always deforms according to a linear combination of two desired deformation modes, regardless of the surface pressure. Thus, the deformation can be recorded with just two strain gauges applied to the face of the feather key. The present work presents the development of a measurement circuit consisting of one Wheatstone quarter bridge, a micro controller and a Bluetooth transmitter unit. Torsion tests are carried out to test the functionality of the measuring circuit.